Enhancing the ultrasonic soldered joint of C_f/Al composite with TC4 alloy by forming a TiAl₃ and carbon fiber synergistically reinforcing structures

In this work, carbon fiber reinforced aluminum matrix composite (C_f/Al) and TC4 alloy were joined by ultrasonic soldering using ZnAl solder. To reduce the soldering temperature, TC4 alloy was initially hot-dipped in molten pure Al with ultrasonic assistance. Results show that a TiAl₃ particle-reinforced Al layer, 80 μm thick, forms on the TC4 surface after 10 s of ultrasonication and 30 min of holding. During soldering, the Al matrix of both the C_f/Al and the TiAl₃ reinforced layer dissolves, exposing the carbon fibers and TiAl₃ particles. These particles and fibers then migrate into the joint under the influence of acoustic vibration and solder squeezing. A fully reinforced joint, synergistically strengthened by both carbon fibers and TiAl₃ particles, is achieved using an ultrasonic power of 1000 W and an ultrasonication time of 12 s. This joint exhibits a shear strength of 30.2 MPa, comparable to the C_f/Al substrate.